Vectronics VEC-813 User Manual
VEC-813/814 Intermod Filter Owner's Manual
Vectronics VEC-813/814 2-Meter FM Intermod Filter
GENERAL INFORMATION
The VEC-813 HT Filter and the VEC-814 Mobile Filter are especially designed to
eliminate squeaks, squawks, bleeps, and other strange noises caused by intermodulation
distortion. These "
signals and out-of-band traffic from pagers, public-service repeaters, aircraft, and other
powerful sources. Intermod signal are not only annoying, in many congested areas they
can render your sensitive wide-band radio useless!
The only cure for intermod is to get rid of the out-of-band signals that cause it. Your
Intermod Filter uses three high-Q bandpass sections plus two low-pass L-sections to form
a razor-sharp network. This knock-out combination passes signals falling within the two
meter band, while attenuating out-of-band interference. Attenuation of unwanted
commercial FM signals approaches -50 dB in most cases, and that's the difference
between extremely strong and completely gone! When the filter is engaged, intermod
vanishes. During transmit, RF sensing automatically switches the filter off-line.
The VEC-813 HT version comes with BNC connectors and is self-powered from a
internal 9-volt battery. The VEC-814 Mobile version uses standard SO-239 connectors
and runs on external 12-VDC. Both models uses state-of-the-art surface-mount
construction and special high-Q porcelain chip capacitors to ensure top performance.
Both are housed in a RF-tight case with an On/Off switch and power LED. The mobile
version uses a standard 2.1mm x 5.5 mm DC plug.
VEC-813 INSTALLATION
phantom signals"
are caused by unwanted mixing between ham-band
Before attempting to use the VEC-813 on your HT, you must install a 9-volt battery. To
do this, remove the two case screws, slip the battery into its spring holder, and install the
snap-clip lead connector. Use a premium-quality Alkaline-type battery for best results.
You may then plug the VEC-813 directly into your HT's BNC antenna connector.
Important: The filter's by-pass sw itching circuit draws power whenever th e VEC-
813's power switch is turned on. For longest battery life, be sure to turn
the unit off when not in use--an d whenever intermod conditi ons do not
require using the filter to copy stations. If your 9-volt battery should
run down while the unit is turned on, the VEC-813 will automatically
default to its "pass-through" mode, and no damage will result.
Important: A 50-mW or greater transmit signal is needed to activate the unit's
automatic by-pass switching. Do not exceed a transmitter RF output
power of 50 Watts, or damage may result. If using an external HT
amplifier, install the VEC-813 between the HT and amplifier.
1
VEC-813/814 Intermod Filter Owner's Manual
VEC-814 INSTALLATION
The VEC-814 may be powered directly from your automotive or 13.5-VDC AC station
power source. Install a standard 2.1 mm x 5.5 mm coaxial-type DC power plug on the
supply line with (+) connected to the center and (-) connected to the barrel. A plug is
supplied with the unit, and extras may be obtained from Radio Shack or other electronic
supply houses. Use standard PL-259 coaxial connectors on the radio and antenna side of
the filter.
Important: Be sure to observe the Radio and Antenna markings when installing the
filter. If you reverse these connections, the filter's RF-sensing circuit
will not work properly and damage to filter components may result!
Also, do not use with tran sceivers w h ere RF outpu t power rating exceed
50-60 Watts.
The VEC-814 will draw a small amount of power to operate the by-pass switching and
RF sensing circuits whenever the unit is switched on. Be sure to switch the unit off when
not in use. Also, the insertion attenuation of the filter is approximately 6-8 dB, and inband signals will be attenuated by this amount whenever it is turned on. While this will
not affect reception in most signal areas, it may degrade reception of very weak signals
A good rule-of-thumb when operating mobile is to leave the VEC-814 off
need it
If power is accidentally removed from you unit while in operation, there is no danger to
your transmitter or to the filter -- the VEC-814 will default to the "pass-through" mode on
both transmit and receive.
.
unless you
IN CASE OF TROUBLE
.
Your Intermod Filter is protected by one-year. If anything goes wrong during the first
year, we'll replace or repair your unit at no charge. However, before contacting the
factory, please check for the symptoms listed below. These are simple difficulties you
can fix yourself.
Filter fails to turn on: Check the power source. For VEC-813, check battery
condition. For VEC-814, check condition of power plug and power source.
Filter fails to disengage during transmit: For VEC-813, is HT power setting on ultra-
low power? For VEC-814, are
2
Radio
and
Antenna
connectors reversed?
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